Polycarbonates and polyarylates are known as coating agents, and are widely used in optical applications, etc. Furthermore, a medical material containing a polycarbonate with cross-linkable silyl groups as an active ingredient has been disclosed (see Japanese Patent Application Kokai No. 58-109062). However, polycarbonates which have such cross-linkable silyl groups suffer from the drawback of being colored a light yellow color, and have therefore conventionally been unsuitable for use as optical coating agents.